vistime: Pretty Timeline Creation

Create timelines or Gantt charts, offline and interactive, that are usable in the 'RStudio' viewer pane, in 'R Markdown' documents and in 'Shiny' apps using 'plotly.js', a high-level, declarative charting library (see <https://plot.ly/javascript>). Hover the mouse pointer over a point or task to show details or drag a rectangle to zoom in. Timelines (and the data behind them) can be manipulated using 'plotly_build()' or, once uploaded to a 'plotly' account, viewed and modified in a web browser.